Outgunned in a one-sided, 20-minute first set, the Swiss player was initially unable to read her 27-year-old opponent's double-handed groundstrokes, clubbed from corner to corner. But Bencic managed to nab the sole break of the second set as she improved her first serve percentage from 33% to 81% and began to anticipate the Russian's patterns with greater ease.

After coming through an epic game to break Diatchenko in the first game of the third set, the former World No.7 took full control of the match. The 20-year-old Bencic made her return from left wrist surgery in September, and since then has raised her ranking from No.312 to No.165 thanks to victory in the St. Petersburg $100,000 ITF tournament and a quarterfinal on her return to WTA level in Linz.

In the semifinals, Bencic will face No.6 seed Ana Bogdan, who disposed of No.3 seed Duan Ying-Ying in a straightforward 6-1, 6-3 encounter - a repeat of the Romanian's first round win at Wimbledon over the Chinese player. The bottom half of the draw will see No.4 seed Hsieh Su-Wei, who dismissed unseeded Austrian Barbara Haas 6-1, 7-5, square off against Viktorija Golubic - another former Top 100 Swiss star seeking to raise her ranking back into that range here.

In her quarterfinal win, Golubic had emerged on top of a tightly played first set against in-form home favorite Luksika Kumkhum, who had thrilled the crowd the previous night with a 6-2, 4-6, 7-6(3) upset of 2009 US Open semifinalist and No.5 seed Yanina Wickmayer.

Kumkhum's double-handed, hyper-aggressive groundstrokes continued to find uncanny angles against Golubic, but the World No.128's solid serving and ability to redirect the ball with her one-handed backhand while in defensive positions was key to edging the first set - and then running away with the second for a 7-6(2), 6-0 win.